Image sensing device including grid structures having different heights

ABSTRACT

An image sensing device is disclosed. The image sensing device includes a pixel array including a plurality of unit pixels, each of which is configured to generate a pixel signal in response to incident light. The pixel array includes a substrate layer including a plurality of photoelectric conversion elements configured to convert the incident light into an electric signal, a plurality of microlenses formed over the substrate layer to respectively correspond to the photoelectric conversion elements, and configured to converge the incident light into the corresponding photoelectric conversion elements, a plurality of color filters disposed between the plurality of photoelectric conversion elements and the plurality of microlenses and configured to transmit light at predetermined wavelengths to corresponding photoelectric conversion elements, and one or more grid structures disposed over the substrate layer at intervals to separate the microlenses and the color filters from adjacent microlenses and the color filter. The grid structures have different heights at different locations in the pixel array such that one or more of the grid structure include a top portion protruding from a top surface of an abutting microlens.

CROSS-REFERENCE TO RELATED APPLICATION

This patent document claims the priority and benefits of Korean patentapplication No. 10-2020-0013093, filed on Feb. 4, 2020, which isincorporated by reference in its entirety as part of the disclosure ofthis patent document.

TECHNICAL FIELD

The technology and implementations disclosed in this patent documentgenerally relate to an image sensing device.

BACKGROUND

An image sensor is a device for converting an optical image intoelectrical signals. With the recent development of automotive, medical,computer and communication industries, the demand for high-performanceimage sensors is rapidly increasing in various devices such as digitalcameras, camcorders, personal communication systems (PCSs), gameconsoles, surveillance cameras, medical micro-cameras, robots, etc.

SUMMARY

Various embodiments of the disclosed technology relate to an imagesensing device capable of improving shading characteristics caused bylenses.

In an embodiment of the disclosed technology, an image sensing devicemay include a pixel array including a plurality of unit pixels, each ofwhich is configured to generate a pixel signal in response to incidentlight. The pixel array may include a substrate layer including aplurality of photoelectric conversion elements configured to convert theincident light into an electric signal, a plurality of microlensesformed over the substrate layer to respectively correspond to thephotoelectric conversion elements, and configured to converge theincident light into the corresponding photoelectric conversion elements,a plurality of color filters disposed between the plurality ofphotoelectric conversion elements and the plurality of microlenses andconfigured to transmit light at predetermined wavelengths tocorresponding photoelectric conversion elements, and one or more gridstructures disposed over the substrate layer at intervals to separatethe microlenses and the color filters from adjacent microlenses and thecolor filters. The grid structures may have different heights atdifferent locations in the pixel array such that one or more of the gridstructure include a top portion protruding from a top surface of anabutting microlens.

In another embodiment of the disclosed technology, an image sensingdevice may include a pixel array including a plurality of unit pixels,each of which is configured to generate a pixel signal corresponding toincident light.

The pixel array may include a substrate layer including a plurality ofphotoelectric conversion elements configured to convert the incidentlight into an electric signal, one or more grid structures disposed atintervals over the substrate layer, and configured to have differentheights at different locations in the pixel array, a plurality of colorfilters disposed in a spacing defined by the grid structures andconfigured to transmit light at predetermined wavelengths tocorresponding photoelectric conversion elements, and a plurality ofmicrolenses disposed over the color filters. The plurality ofmicrolenses may be consecutively arranged and, as a whole, forms acurved shape that is thinner at a center portion of the pixel array andthicker at an edge portion of the pixel array.

In another embodiment of the disclosed technology, an embodiment of thedisclosed technology, an image sensing device may include a pixel arrayin which a plurality of unit pixels, each of which is configured togenerate a pixel signal corresponding to incident light, is arranged.The pixel array may include a substrate layer provided with a pluralityof photoelectric conversion elements configured to perform photoelectricconversion of the incident light, a plurality of microlenses formed overthe substrate layer so as to respectively correspond to thephotoelectric conversion elements, and configured to converge theincident light into the corresponding photoelectric conversion elements,a plurality of color filters configured to filter out visible light fromlight having penetrated the microlenses, and one or more grid structuresdisposed over the substrate layer so as to define a region in which themicrolenses and the color filters are formed. The grid structures may beformed in a manner that some regions thereof protrude outward from aspacing between the microlenses and have different heights according towhere they are formed in the pixel array.

In another embodiment of the disclosed technology, an image sensingdevice may include a pixel array in which a plurality of unit pixels,each of which is configured to generate a pixel signal corresponding toincident light, is arranged.

The pixel array may include a substrate layer provided with a pluralityof photoelectric conversion elements configured to perform photoelectricconversion of the incident light, one or more grid structures disposedover the substrate layer, and configured to have different heightsaccording to where the grid structures are formed in the pixel array, aplurality of color filters disposed in a spacing defined by the gridstructures, and configured to filter out visible light from the incidentlight, and a plurality of microlenses disposed over the color filters.The plurality of microlenses may be formed in a curved shape in whichthe microlenses gradually increase in height in a direction from acenter portion of the pixel array to an edge portion of the pixel arrayand contiguous microlenses are consecutively coupled to one another.

It is to be understood that both the foregoing general description andthe following detailed description of the disclosed technology areillustrative and explanatory and are intended to provide furtherexplanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example of a block diagram illustrating an image sensingdevice based on some implementations of the disclosed technology.

FIG. 2 is a cross-sectional view illustrating an example of a pixelarray taken along the line A-A′ shown in FIG. 1 .

FIG. 3A is a cross-sectional view illustrating an example of a gridstructure shown in FIG. 2 .

FIG. 3B is a cross-sectional view illustrating another example of thegrid structure shown in FIG. 2 .

FIG. 4 is a cross-sectional view illustrating another example of thepixel array taken along the line A-A′ shown in FIG. 1 .

FIG. 5 is a cross-sectional view illustrating still another example ofthe pixel array taken along the line A-A′ shown in FIG. 1 .

DETAILED DESCRIPTION

This patent document provides implementations and examples of an imagesensing device that can mitigate shading and optical crosstalk issuescaused by lenses. In some implementations of the disclosed technology,an image sensing device can mitigate such issues by increasing theamount of light incident upon photoelectric conversion elements such asphotodiodes, while minimizing expansion of the air layer within the gridstructure.

Reference will now be made in detail to certain embodiments, examples ofwhich are illustrated in the accompanying drawings. Wherever possible,the same reference numbers will be used throughout the drawings to referto the same or similar parts. In the following description, a detaileddescription of related known configurations or functions incorporatedherein will be omitted to avoid obscuring the subject matter.

FIG. 1 is a block diagram illustrating an example of an image sensingdevice based on some implementations of the disclosed technology.

In some implementations, the image sensing device may include a pixelarray 100, a correlated double sampler (CDS) 200, an analog-to-digitalconverter (ADC) 300, a buffer 400, a row driver 500, a timing generator600, a control register 700, and a ramp signal generator 800.

The pixel array 100 may include unit pixels (PXs) consecutively arrangedin rows and columns in a two-dimensional (2D) array. Each of the unitpixels (PXs) may convert incident light into an electrical signal togenerate a pixel signal, which is sent to the correlated double sampler(CDS) 200 through column lines. Each unit pixel (PX) may include one ormore photoelectric conversion elements formed in a substrate. In someimplementations, the substrate may include a first surface upon whichlight reception structures are formed and a second surface facing awayfrom the first surface. The light reception structures can allowincident light to converge upon the photoelectric conversion elements ofunit pixels. The light reception structure may include color filters,one or more grid structures, and microlenses. The pixel array 100implemented based on some embodiments of the disclosed technology mayinclude a light reception structure capable of mitigating shadingeffects, as will be discussed below.

The correlated double sampler (CDS) 200 may be used to remove anundesired offset value of pixels by sampling a pixel signal twice toremove the difference between these two samples. In someimplementations, the correlated double sampler (CDS) 200 may sample andhold electrical image signals received from the pixels (PXs) of thepixel array 100. For example, the correlated double sampler (CDS) 200may perform sampling of a reference voltage level and a voltage level ofthe received electrical image signal in response to a clock signalreceived from the timing generator 600, and may generate an analogsignal corresponding to a difference between the reference voltage leveland the voltage level of the received electrical image signal. Theanalog signal is sent to the analog-to-digital converter (ADC) 300 fordigitalization.

The analog-to-digital converter (ADC) circuit 300 is used to convertanalog signals to digital signals. Examples of the analog-to-digitalconverter (ADC) circuit 300 may include a ramp-compare typeanalog-to-digital converter that compares the analog pixel signal with areference signal such as a ramp signal that ramps up or down, and atimer counts until a voltage of the ramp signal matches the analogsignal. In some implementations, the analog-to-digital converter (ADC)300 may compare a ramp signal received from the ramp signal generator800 with a sampling signal received from the correlated double sampler(CDS) 200 to determine whether the voltage level of the ramp signalmatches the voltage level of the sampling signal. The analog-to-digitalconverter (ADC) 300 may receive clock signals from the timing generator600 to count the clock signals until the voltage level of the rampsignal matches the voltage level of the sampling signal, and may outputa count value as a converted digital signal to the buffer 400.

The buffer 400 may temporarily store each of the digital signalsreceived from the analog-to-digital converter (ADC) 300, and may senseand amplify each of the digital signals to output each of the amplifieddigital signals. Therefore, the buffer 400 may include a memory (notshown) and a sense amplifier (not shown). The memory may store the countvalue, which is a digital signal converted from the output signals ofthe plurality of unit pixels (PXs). The sense amplifier may sense andamplify each count value received from the memory.

The row driver 500 may selectively activate the pixel array 100 on a rowline basis in response to an output signal of the timing generator 600.For example, the row driver 500 may generate a selection signal toselect any one of the plurality of row lines.

The timing generator 600 may generate a timing signal to control theoperations of the row driver 500, the correlated double sampler (CDS)200, the analog-to-digital converter (ADC) 300, and the ramp signalgenerator 800.

The control register 700 may generate control signals to control theoperations of the ramp signal generator 800, the timing generator 600,and the buffer 400.

The ramp signal generator 800 may generate a ramp signal to process animage signal transmitted to the buffer 400 in response to a controlsignal received from the control register and a timing signal receivedfrom the timing generator 600.

FIG. 2 is a cross-sectional view illustrating an example of the pixelarray 100 taken along the line A-A′ shown in FIG. 1 .

In some implementations, the pixel array 100 of the image sensing devicemay include a substrate layer 110 and a light reception layer 120.

The substrate layer 110 may include a semiconductor substrate. Thesemiconductor substrate may include a first surface upon which the lightreception layer 120 is disposed and a second surface facing away fromthe first surface. The semiconductor substrate 110 may include amaterial in a monocrystalline state. In one example, the semiconductorsubstrate 110 may include a silicon-containing material. That is, thesemiconductor substrate 110 may include a monocrystallinesilicon-containing material. The semiconductor substrate 110 may includeP-type impurities diffused or implanted therein. The semiconductorsubstrate 110 may include photoelectric conversion elements 112 suchthat each unit pixel (PX) includes one of the photoelectric conversionelements 112. Each of the photoelectric conversion elements 112 mayconvert incident light received through a light reception layer 120 intoan electrical signal.

Each of the photoelectric conversion elements 112 may include an organicor inorganic photodiode. The photoelectric conversion element 112 mayinclude impurity regions vertically stacked within the semiconductorsubstrate layer 110. For example, each of the photoelectric conversionelements 112 may include a photodiode in which an N-type impurity regionand a P-type impurity region are vertically stacked on top of oneanother. The N-type impurity region and the P-type impurity region maybe formed by ion implantation. The photoelectric conversion elements 112may be isolated from adjacent photoelectric conversion elements, therebyunit pixels are isolated from each other by device isolation layers (notshown). The device isolation layer may include a deep trench isolation(DTI) structure.

The disclosed technology may be implemented in various embodiments toprovide a pixel array of the image sensing device that includesmicrolenses and grid structures disposed therebetween that are formed tohave different thicknesses depending on their locations in the pixelarray such that the thicknesses of the microlenses at edges of theimaging pixel array are thicker than those at the center of the imagingpixel array.

The light reception layer 120 may be formed over the first surface ofthe substrate layer 110. The light reception layer 120 may include acolor filter layer 122, a lens layer 124, and a grid structure 126.

The color filter layer 122 may include optical filters located above thephotoelectric conversion elements 112 to filter the light to be detectedby the photoelectric conversion elements 112. In some implementations,the color filter layer 122 may transmit visible light at a certainwavelength while blocking light at other wavelengths. The color filterlayer 122 may include a plurality of color filters. Each unit pixel (PX)includes at least one color filter structured to fill the lower parts ofthe gaps between the grid structures 126. For example, the color filterlayer 122 may include a plurality of red color filters (Rs), a pluralityof green color filters (Gs), and a plurality of blue color filters (Bs)such that each unit pixel (PX) includes a red color filter, a greencolor filter, or blue color filter. Each red color filter (R) maytransmit only red light from among RGB lights of visible light. Eachgreen color filter (G) may transmit only green light from among RGBlights of visible light. Each blue color filter (B) may transmit onlyblue light from among RGB lights of visible light. In an implementation,the red color filters (Rs), the green color filters (Gs), and the bluecolor filters (Bs) may be arranged in a Bayer pattern. In anotherimplementation, the color filter layer 122 may include a plurality ofcyan color filters, a plurality of yellow color filters, and a pluralityof magenta color filters.

The lens layer 124 may converge incident light and direct the convergedlight onto the color filter layers 122. To this end, the lens layer 124may be disposed over the color filter layer 122, and, in someimplementations, each microlens of the lens layer 124 may be formed ineach space defined by the grid structures 126. For example, the lenslayer 124 may include microlenses formed over the respective colorfilters, and the microlenses may be formed in the spaces defined by thegrid structures 126 in a manner that the microlenses are lower in heightthan the grid structures 126. In some embodiments of the disclosedtechnology, the microlenses may have the same or similar size. Forexample, the microlenses may have the same or similar height and thesame or similar width to have the same or similar radius of curvature(RoC).

The grid structures 126 are arranged at intervals over the upper portionof the substrate layer 110. Each pair of color filter and microlens isformed between two adjacent grid structures 126, which are formed toprevent optical crosstalk from occurring between adjacent color filters.In some implementations, the grid structures 126 may have differentheights according to where they are formed in the pixel array 100. Forexample, the grid structures 126 may be formed to gradually increase inheight in the direction from the center portion of the pixel array 100to the edge portion of the pixel array 100.

In an implementation where an objective lens (not shown) disposed overthe pixel array 100 and incident light is converged on the pixel array100 by the objective lens, the incident light at the center portion ofthe pixel array 100 propagates in a direction substantiallyperpendicular to the plane on which the pixel array 100 is arranged.Different from the light at the center portion of the pixel array 100,the incident light at the edge portion of the pixel array 100 propagatesobliquely with respect to the optical axis of the pixel array 100. Thecloser it gets to the edge of the pixel array 110, the larger the angleof incidence of the light. This may lead to shading phenomenon, and thusthe edge portion of the image obtained from the pixel array 100 appearsdarker than the image from the center portion of the pixel array 100.

In order to avoid or minimize such shading, the image sensing devicebased on some implementations of the disclosed technology may allow thegrid structures 126 to have different heights depending on theirlocations in the pixel array such that the height of the grid structureis shortest at the center portion of the pixel array 100 (or shorter atthe center portion than the edge portion) and gradually increase asapproaching the edge portion of the pixel array 100. As such, the gridstructures 126 may be formed in a manner that top surfaces of the gridstructures 126 protrude from the top surface of the lens layer 124, moreat the edge portion than at the center portion.

FIG. 3A is a cross-sectional view illustrating an example of the gridstructure shown in FIG. 2 , focusing on only some grid structures formedat the center portion of the pixel array 100.

In some implementations, the grid structures 126 can include a low-indexmaterial layer that is structured to separate the plurality of colorfilters from one another to provide optical isolation between adjacentcolor filters. In one example, the grid structures 126 may include alow-index layer such as an air layer 126 a and a capping film 126 bstructured to cover the air layer 126 a.

The capping film 126 b may be the outermost layer of the multi-layergrid structure 126.

In some implementations, the grid structure 126 may be formed in amanner that some parts of the air layer 126 a protrude outward from thelens layer 124. Specifically, as can be seen from FIG. 2 , the gridstructures 126 may have different heights depending on their locationsin the pixel array such that the height of the grid structure isshortest at the center portion of the pixel array 100 and graduallyincrease in height as approaching the edge portion of the pixel array100. The air layer 126 a formed to protrude outward from the lens layer124 as described above can increase light reflection over the colorfilter layer 122, directing more light rays into photoelectricconversion elements of each unit pixel.

In addition, the protruding portion of the air layer 126 a can helpprevent rupture by distributing pressure across the protruding portionof the air layer 126 a when the air layer 126 a expands.

If the lens layer or the color filter layer is formed to cover the topsurface of the grid structure, the pressure applied across the air layermay affect the color filter layer and the lens layer, and at worst thegrid structure may be collapsed or ruptured. However, the protrudingstructure of the air layer 126 a implemented based on some embodimentsof the disclosed technology can prevent the pressure from exceeding theallowable level by allowing air contained in the air layer 126 a to bedischarged outside through the capping film 126 b of the protrudedportion of the air layer.

To this end, the capping film 126 b may be formed of a material filmthat allows air of the air layer to be discharged outside therethrough.For example, the capping film 126 b may include an ultra low temperatureoxide (ULTO) film such as a silicon oxide film (SiO₂). The capping film126 b may be formed as thin as possible to discharge air of the airlayer 126 a outside. In some implementations, the capping film 126 b maybe formed to a thickness of 300 Å or less.

The capping film 126 b may be formed to extend to a region below thecolor filter layer 122. That is, the capping film 126 b may be formed toextend to a region between the substrate layer 110 and the color filterlayer 122. In some implementations, the capping film 128 formed belowthe color filter layer 122 may operate as a buffer layer forplanarization of the layers on the substrate layer 110.

As described above, the grid structures 126 based on someimplementations of the disclosed technology may be formed to havedifferent heights depending on their locations in the pixel array suchthat the height of the grid structure is shorter at the center portionof the pixel array 100 and gradually increase in height as approachingthe edge portion of the pixel array 100, reducing shading effects. Inaddition, the grid structure 126 may include the protruding portion atthe spacing between the microlenses, such that the amount of lightincident upon each photoelectric conversion element of the pixel array100 may increase and the air layer 126 a can be prevented fromexcessively expanding.

FIG. 3B is a cross-sectional view illustrating another example of thegrid structure 126 shown in FIG. 2 .

In some implementations, the grid structure 126 may include an air layer126 a′, a capping film 126 b′, a metal layer 126 c, and an insulationfilm 126 d. In other words, the grid structure 126 may be formed as ahybrid structure composed of the air layer 126 a′ and the metal layer126 c.

The capping film 126 b′ may be a material film formed at the outermostlayer of the grid structure 126, and may cover the air layer 126 a′, themetal layer 126 c, and the insulation film 126 d.

The capping film 126 b′ shown in FIG. 3B may be identical in materialand structure to the capping film 126 b shown in FIG. 3A.

As can be seen from FIG. 3B, the grid structure 126 may be formed in amanner that some parts of the air layer 126 a′ protrude outward from thelens layer 124. The metal layer 126 c may be formed below the air layer126 a′. For example, the metal layer 126 c may be formed between thesubstrate layer 110 and the air layer 126 a′. The metal layer 126 c mayinclude tungsten (W). Alternatively, the metal layer 126 c may include atungsten film and a barrier metal layer formed below the tungsten film.

The insulation film 126 d may be formed to cover a top surface and sidesurfaces of the metal layer 126 c, such that expansion of such metalmaterial can be prevented in a thermal annealing process. For example,the insulation film 126 d may be formed between the air layer 126 a′ andthe metal layer 126 c and between the capping film 126 b′ and the metallayer 126 c.

The insulation film 126 d may be formed to extend to a region below thecolor filter layer 122 in the same manner as in the capping film 126 b′.The capping film 128 and the insulation film 129 formed below the colorfilter layer 122 may be used as a buffer layer formed between thesubstrate layer 110 and the color filter layer 122.

FIG. 4 is a cross-sectional view illustrating another example of thepixel array 100 taken along the line A-A′ shown in FIG. 1 .

In some implementations, the pixel array 100 of the image sensing devicemay include a substrate layer 110 and a light reception layer 120′.

The substrate layer 110 shown in FIG. 4 is identical in structure to thesubstrate layer 110 shown in FIG. 2 , and as such a detailed descriptionthereof will herein be omitted for brevity.

The light reception layer 120′ may be disposed over the first surface ofthe substrate layer 110, and may include a color filter layer 122, alens layer 124′, and a grid structure 126.

The color filter layer 122 may include optical filters located above thephotoelectric conversion elements 112 to filter the light to be detectedby the photoelectric conversion elements 112. In some implementations,the color filter layer 130 may transmit visible light at a certainwavelength while blocking light at other wavelengths. The color filterlayer 122 may include a plurality of color filters. Each unit pixel (PX)includes at least one color filter structured to fill the lower parts ofthe gaps between the grid structures 126.

The lens layer 124′ may converge incident light and direct the convergedlight onto the color filter layer 122. To this end, the lens layer 124′may be disposed over the color filter layer 122, in someimplementations, each microlens of the lens layer 124′ may be formed ineach space defined by the grid structures 126. Specifically, the lenslayer 124′ may include a plurality of microlenses corresponding to therespective unit pixels, and the microlenses may have different heightsdepending on positions of the corresponding unit pixels. For example,the microlenses may be formed to have different heights depending ontheir locations in the pixel array such that the heights of themicrolenses are shortest at the center portion of the pixel array 100and gradually increase in height as approaching the edge portion of thepixel array 100. However, RoC (radius of curvature) values of themicrolenses may be identical or similar to each other irrespective ofthe position of the unit pixels.

The grid structures 126 may be arranged at intervals over the upperportion of the substrate layer 110. Each pair of color filter andmicrolens is formed between two adjacent grid structures 126, which areformed to prevent optical crosstalk from occurring between adjacentcolor filters. In some implementations, the grid structure 126 may havedifferent heights depending on their locations in the pixel array suchthat the height of the grid structure is shortest at the center portionof the pixel array 100 (or shorter at the center portion than the edgeportion) and gradually increase in height as approaching the edgeportion of the pixel array 100. In addition, the grid structure 126 mayinclude a structure composed of the air layer and the capping film asshown in FIG. 3A, or may include a structure composed of the metallayer, the air layer, and the capping film as shown in FIG. 3B. In thiscase, the grid structure 126 may protrude from the lens layer 124′, andsome parts of the air layer may protrude outward from the spacingbetween the microlenses of the lens layer 124′.

As shown in FIG. 4 , the pixel array implemented based on someembodiments of the disclosed technology may be formed in a manner thatboth the grid structures 126 and the lens layers 124′ have differentheights depending on their locations in the pixel array such that theheight of the grid structure and the lens layers 124′ are shortest atthe center portion of the pixel array 100 (or shorter at the centerportion than the edge portion) and gradually increase in height asapproaching the edge portion of the pixel array 100.

FIG. 5 is a cross-sectional view illustrating still another example ofthe pixel array 100 taken along the line A-A′ shown in FIG. 1 .

In some implementations, the pixel array 100 of the image sensing devicemay include a substrate layer 110 and a light reception layer 120″.

The substrate layer 110 shown in FIG. 5 is identical or similar to thesubstrate layer 110 shown in FIG. 2 , and thus can be implemented in thesame way as discussed above.

The light reception layer 120″ may be disposed over the first surface ofthe substrate layer 110, and may include a color filter layer 122, alens layer 124″, and a grid structure 126.

The color filter layer 122 may include optical filters located above thephotoelectric conversion elements 112 to filter the light to be detectedby the photoelectric conversion elements 112. In some implementations,the color filter layer 130 may transmit visible light at a certainwavelength while blocking light at other wavelengths. The color filterlayer 122 may include a plurality of color filters. Each unit pixel (PX)includes at least one color filter structured to fill the lower parts ofthe gaps between the grid structures 126.

The lens layer 124″ may converge incident light and direct the convergedlight onto the color filter layer 122. The lens layer 124″ may include aplurality of microlenses corresponding to the respective unit pixels,and the microlenses may have different heights depending on theirlocations in the pixel array. Specifically, the lens layer 124″ may havedifferent heights depending on their locations in the pixel array suchthat the height of the lens layer 124″ is shortest at the center portionof the pixel array 100 (or shorter at the center portion than the edgeportion) and gradually increase in height as approaching the edgeportion of the pixel array 100, thereby forming a curved shape as awhole. For example, the thickness of the lens layer 124″ may graduallyincrease as approaching the edge portion of the pixel array 100 from thecenter portion of the pixel array 100. In this case, each of themicrolenses may not be formed to have a curved RoC (radius of curvature)value, and the contiguous (or adjacent) microlenses may be consecutivelyarranged.

The grid structures 126 are arranged at intervals over the upper portionof the substrate layer 110. Each pair of color filter and microlens isformed between two adjacent grid structures 126 to prevent opticalcrosstalk from occurring between color filters contiguous to each other.The grid structure 126 may gradually increase in height as approachingthe edge portion of the pixel array 100 from the center portion of thepixel array 100, as depicted in FIG. 2 or FIG. 4 . In addition, the gridstructure 126 may include a structure composed of the air layer and thecapping film as shown in FIG. 3A, or may include a structure composed ofthe metal layer, the air layer, and the capping film as shown in FIG.3B.

As is apparent from the above description, the image sensing devicebased on the embodiments of the disclosed technology can reduce shadingeffects that can be caused by lenses.

The image sensing device based on the embodiments of the disclosedtechnology can increase the amount of light incident upon photoelectricconversion elements, while preventing expansion of the air layer withinthe grid structure.

Those skilled in the art will appreciate that the embodiments may becarried out in other specific ways than those set forth herein.

Although a number of illustrative embodiments have been described, itshould be understood that numerous other modifications and embodimentscan be devised based on what is disclosed and/or illustrated.

What is claimed is:
 1. An image sensing device comprising: a pixel arrayincluding a plurality of unit pixels, each of which is configured togenerate a pixel signal in response to incident light; wherein the pixelarray includes: a substrate layer including a plurality of photoelectricconversion elements configured to convert the incident light into anelectric signal; a plurality of microlenses formed over the substratelayer to respectively correspond to the photoelectric conversionelements, and configured to converge the incident light into thecorresponding photoelectric conversion elements; a plurality of colorfilters disposed between the plurality of photoelectric conversionelements and the plurality of microlenses and configured to transmitlight at predetermined wavelengths to corresponding photoelectricconversion elements; and one or more grid structures disposed over thesubstrate layer at intervals to separate the microlenses and the colorfilters from adjacent microlenses and the color filters, wherein thegrid structures have different heights at different locations in thepixel array such that one or more of the grid structures include a topportion protruding from a top surface of an abutting microlens, whereinthe grid structures include an air layer and a capping film formed tocover the air layer, and wherein the grid structures are formed in amanner that some regions of the air layer protrude outward from aspacing between the microlenses.
 2. The image sensing device accordingto claim 1, wherein the heights of the grid structures are shorter at acenter portion of the pixel array than at an edge portion of the pixelarray and gradually increase in height as approaching the edge portionof the pixel array.
 3. The image sensing device according to claim 1,wherein the plurality of microlenses is formed to have substantially thesame height.
 4. The image sensing device according to claim 1, whereinthe plurality of microlenses is formed to have different heightsdepending on their locations in the pixel array.
 5. The image sensingdevice according to claim 4, wherein the plurality of microlenses isformed to have different heights depending on their locations in thepixel array such that the heights of the microlenses are shorter at acenter portion of the pixel array than at an edge portion of the pixelarray and gradually increase in height as approaching an edge portion ofthe pixel array.
 6. The image sensing device according to claim 1,wherein the respective microlenses have substantially the same radius ofcurvature (RoC).
 7. The image sensing device according to claim 1,wherein the capping film is formed to extend to regions below the colorfilters.
 8. The image sensing device according to claim 1, wherein thegrid structures include: a metal layer disposed over the substratelayer; an air layer disposed over the metal layer; and a capping filmformed to cover the air layer and the metal layer.
 9. The image sensingdevice according to claim 8, further comprising: an insulation filmformed to cover a top surface of the metal layer and side surfaces ofthe metal layer.
 10. The image sensing device according to claim 9,wherein the insulation film is formed to extend to regions below thecolor filters.
 11. The image sensing device according to claim 8,wherein the grid structures are formed in a manner that a portion of theair layer protrude from a top surface of abutting microlenses.